This invention is directed to a novel coating composition and in particular to a coating composition which forms flexible and ductile finishes on metal.
A current method for preparing cans utilized for packaging foodstuffs is to draw a flat aluminum or steel sheet into a low profile can body and then redraw this can into a deep can body by a second drawing step and optionally a bead is crimped on the open edge of the can. The can is then cleaned and a coating is sprayed on and baked. The cost of producing these cans can be substantially reduced by coating the aluminum or steel sheet before it is drawn with a flexible and ductile finish which will not fracture, crack or peel during the forming of the can. This elminates the separate coating step. Currently, polyvinyl chloride coatings have been used as formable finishes on the aluminum sheet. However, after forming the can and particularly after forming the bead, a large number of failures of the finish due to cracks and peeling of the finish have been noted; and also, the finish is not resistant to food staining such as staining with pumpkins, tomatoes, tomato soup or ketchup.
The novel composition of this invention which utilizes a blend of an acrylic polymer and an epoxy resin forms a finish which is ductile, and has good adhesion to the metal substrate and is resistant to food staining.